Making your lungs last longer - Viking style!

As I've moved to Ireland, this post will be in English (Irish might have been more fitting, but I'm not quite ready for that).
[The introduction is rater long, so skip to "Now starts the magic" if you just want to see the pretty pictures]

Last New Year I was in Norway with a group of alumni sports students from the university I attended in Denmark. Being from Denmark, having ventured all the way to "Rondetunet" (930 m, sat image here), we thought ourselves at quite an altitude. Well into New Years Eve, also here celebrated with some amount of alcohol indulgence, the inevitable happens as we start reminiscing over past mountain experiences - someone has a great idea!
"I wonder if one can counteract the effects of altitude by simply holding ones breath and compressing the lung cavity before exhaling, thus mimicking the pressure found at lower altitudes...?" As it was one of the blokes who came upon this inspired thinking, the question was accompanied with a considerate amount of chin scratching (all danish males have beards, for extra chin scratching effect).

Being scientists, and tipsy, we decided to fashion an experiment to find out just how much (over) pressure one can generate in the lung cavity. The one challenge was to find out how to measure said pressure in the middle of the night, in the middle of nowhere, on a cold Norwegian New Years night.
Que empty box-wine bags. Someone had remembered a bit of physics mentioning something about pressure being equal to force times area. So with an air container at hand, all we needed was a way to measure the force over a know area. Luckily wine box volumes are slightly smaller than the volume of the bag they contain. After cutting out the end of a box (every one has knives this far north) you end up with a box, with one end made up by the wine bag, and a surface are constricted by the wine box. We then agreed that we could measure force by multiplying the readout we could generate on a bathroom scales with the local gravitational constant (9.82 N/kg in Norway).

Now starts the magic.
Having wedged the wine box between a table and the scales so that all force from expanding the wine bag would be directed down through the cut-out bottom of the wine box onto the scales, all the force generated by blowing into the wine bag, should be transferred onto the scales. Because we knew the area of the cut-out and could read the resulting kg off the scales we could figure out the pressure in the bag. Now it was time to blow! Considering the amount of enthusiasm involved when designing the setup, only 4 brave people were ready to blow into the bag.

Figure 1. Pressure exerted as a percentage of sea level pressure compared to the body weight of the blower. Shapes are individuals, they grey zone indicates a rough 95 % confidence interval of the willing population. 

The four! repetitions showed that we could generate 8.9 % of surface pressure (101300 Pa), or 9060 Pa of over pressure (sometimes called gauge pressure). While this is all wildly exiting, it's more fun to know how far up Everest you can go with our newly found technique!
So here we go! The most confusing graph you'll see today:

Figure 2. Partial pressure of oxygen versus altitude. The blue line is the equivalent partial pressure when breathing normally. The red line is the partial pressure equivalent when holding and compressing breath before exhaling .No, I'm not taking into account that earth is an ellipsoid.

In the figure I've added some lines, representing the partial pressure of oxygen at notable height references. "Rondetunet" is the site of idea conception, and while not being very high up, it is a stunning location! "La Rinconada" is a village in Peru, that sits very close the the "Highest Livable Altitude", where one can live a normal (but permanently exhausted) life, with working digestion etc. At 8000 meters is the "Death Zone", over which you simply just start to die...
Here is the interesting part - look at the graph! The red curve doesn't reach the "Death Zone" limit before 10,000 meters! We can all climb Everest without oxygen!

But why don't we then...?

Turns out that while you theoretically can increase the partial pressure enough to survive, you run into a problem of lung size. Because the air you breathe in is not compressed, at 8000 meters you only breathe in 35 % of the molecules you would at sea level. The pressure of that air is roughly 35600 Pa, when you add you squeezing power of 9060 Pa, you not only increase the pressure, you also decrease the volume by 25 %. Of the top of my head the vital capacity for humans is something like 3.5 L, so this compression ratio should not be a problem. What is a problem however, is the aforementioned lack of air-molecules on the intake. Using our "pulmar compression technique" (soon to be patented) you can increase the saturation of you red blood cells slightly, but you cannot take in more air! In other words, the available oxygen per breath at 8000 meters is still 65 % lower than at sea level, no matter how hard you squeeze.
So yes, while you probably could lie still and just breathe quite high up, as soon as you start moving, and you need to ventilate, you'd want to head downhill fast!

There could be a whole section here dealing with falling CO2 concentration and hemoglobin cooperativity, but if you're that into it, go find a university, or have a look on youtube!

Thanks for reading about one of the most fun science experiments I've participated in (there's more of them elsewhere in this blog!)